The effect of substrate bias voltage on the properties of Al-doped ZnO films deposited by magnetron sputtering

Our work aims to investigate the influence of substrate bias voltage on the structure, optical, and electrical properties of ZnO:Al thin films deposited on Si (100) and glass substrates by radio frequency magnetron sputtering. We have applied the layer-by-layer growth method in magnetron sputtering. X-ray diffraction, atomic force microscopy, Raman scattering, photoluminescence, Fourier transform infrared spectrometry, multi-angle spectral ellipsometry, optical transmission, and electrical measurements were used to characterize samples. It was found that the negative bias voltage applied to the substrate holder during film growth caused an increase in the conductivity of ZnO:Al films four times compared with ZnO:Al films grown without external bias voltage. The concentration of Al donor impurity was increased in ZnO:Al films with increasing the negative bias voltage applied to the substrate.